How to Resteore my Touch 2G?

i have downloaded the file "iPod2,1_2.2.1_5H11a_Restore.zip to restore my iPod to the old firmware. After unraring the file i can only see *dmg files and some other. The *ipsw file is not inside the folder. Normaly, i use iTues pushing the shift button and the restore button. But without *ipsw file, iTunes can't restore my iPod.